Studying the effect of spraying parameters on the sintering of YSZ TBC using APS method

Plasma spray coatings 8YSZ (Zirconia stabilized with 8 wt% Yttria) are widely used for the protection of gas turbine parts against heat. Operating temperature of turbine engine causes sintering of the coating and this alters the microstructure of the coating. Sintering rate is dependent on the primary microstructure of the coating. The objective of this study is to compare the effect of spraying parameters on the sintering rate of YSZ TBC. Therefore, the effect of Hydrogen flow rate, powder feed rate and spray angle on sintering was studied. Sintering in constant temperature of 1100 °C for 10, 20, 50, 100 and 150 h was conducted in the environment atmosphere furnace. Microstructure studying was conducted using OM and FESEM and phase studying was conducted with XRD. Porosity and hardness measurement were considered as a measure of sintering. The results showed that the initial conditions of the coatings (the size and quantity of pores and residual stress) have a tremendous impact on the sintering behavior, such that a higher percent of the pores and smaller porosities increase sintering rate.